This application claims the priority of German Application No. 197 45 128.4, filed Oct. 13, 1997, the disclosure of which is expressly incorporated by reference herein.
The invention relates to a method for determining the triggering threshold value for an automatic braking operation.
A method of the above-mentioned type for triggering an automatic braking operation is known from German Patent document DE 44 22 664 A1. In the case of this method, an automatic braking operation is triggered before the brake pedal is operated if, as a necessary criterion, the operating speed (vg) during the release of the gas pedal exceeds a triggering threshold value. According to German Patent document DE 44 22 664 A1, on which this application is based, this required criterion is not sufficient; that is, for the actual triggering of the automatic braking operation, it is required that additional criteria be met.
In this case, it is difficult to determine a specific magnitude of the triggering threshold value at which the automatic braking operation is triggered. If the braking operation is triggered too frequently, the driving comfort can be significantly impaired. On the other hand, if the triggering does not take place as required, the braking distance is extended unnecessarily in comparison to a case in which an automatic braking operation is triggered.
There is therefore needed a method which adapts the triggering threshold value to the driver's actions to thus achieve a more reliable separation between required and not required triggerings of the automatic braking operation.
These needs are met by a method for determining a triggering threshold value for an automatic braking operation, in which the automatic braking operation is triggered before the brake pedal is operated by the driver, and a required condition for triggering the braking operating is that, when the gas pedal is released, the operating speed exceeds a triggering threshold value. The triggering threshold value is determined as a function of detected magnitudes which represent the driver's actions in the driving operation.
According to the invention, at least one value is detected which represents the driver's vehicle handling and, based on this value, the triggering threshold for the automatic braking operation is determined. In this case, it is unimportant whether the necessary criterion for triggering the automatic braking operation is sufficient or whether additional criteria are required for this purpose, such as the determination of the transfer of the driver's foot from the gas pedal to the brake pedal.
According to the advantageous further embodiments of the present invention, the operating speed of the clutch pedal or of the gear change shifting lever is used as the value representing the driver's actions. In addition to or independently thereof, the operating speed of the gas pedal or of the brake pedal can also be detected and correspondingly analyzed. According to a further advantageous embodiment, in the case of vehicles with automatic transmissions, the frequency of the kick-down operations of the gas pedal is analyzed. According to the further embodiments, the acceleration or the deceleration of the vehicle itself is used for detecting the driver's actions and for correspondingly adapting the triggering threshold value.
In general, it should be stressed that, as the value of the detected magnitudes rises, a higher value of the triggering threshold is established. In this case, the above-mentioned magnitudes can be used individually or in combinations for determining the triggering threshold value. This takes place, for example, by means of a multi-dimensional characteristic diagram.
The drawing illustrates examples of the different characteristic curves of the individual magnitudes. The combination of the individual characteristic curves can be carried out by a simple mutual linking as well as by adapted multi-dimensional characteristic diagrams.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.